Saponification Value Calculator
Calculate the saponification value (SAP value) of an oil — the amount of KOH needed to saponify one gram of oil — for soap making.
Formula
Lye (g) = Oil (g) × SAP value × lye factor × (1 − superfat%)
- SAP values are for NaOH (bar soap). Multiply by 1.403 for KOH (liquid soap).
- Superfat (lye discount) leaves extra unsaponified oils for a milder soap.
- Water amount: typically 30–38% of oil weight, or 2.3:1 water:lye by weight.
100 g coconut oil, NaOH, 5% superfat
Inputs
- Oil Mass: 100 g
- Oil Type: coconut
- Lye Type: naoh
- Superfat / Lye Discount: 5 %
NaOH = 100 × 0.190 × 1 × 0.95 = 18.05 g.
Frequently asked questions
What is superfat?
A small percentage of unsaponified oil left in soap to make it more moisturizing and skin-friendly.
Is KOH or NaOH for bar soap?
NaOH (sodium hydroxide) makes hard bar soap. KOH (potassium hydroxide) makes soft or liquid soap.